People generate a large and ever-increasing volume of waste, which originates in rural and urban areas, industrial operations and other activities. In spite of waste recycling, which is the solution to the huge amount of solid waste, a large part of it is deposited into landfills, dumps, etc.Landfills are, at present, the most widely used waste disposal facilities. Final cover systems are used at landfills and other types of waste disposal sites to control moisture and percolation, promote... Show morePeople generate a large and ever-increasing volume of waste, which originates in rural and urban areas, industrial operations and other activities. In spite of waste recycling, which is the solution to the huge amount of solid waste, a large part of it is deposited into landfills, dumps, etc.Landfills are, at present, the most widely used waste disposal facilities. Final cover systems are used at landfills and other types of waste disposal sites to control moisture and percolation, promote surface water runoff, and minimize erosion. In addition, covers prevent direct exposure to the waste, control gas emissions and odors, prevent occurrence of disease vectors and other nuisances, and meet aesthetic and other end-use purposes. The Resource Conservation and Recovery Act (RCRA) Subtitle D, requires the use of landfill covers to meet these needs.Prescribed covers, permitted by current regulations, are based on a barrier concept that requires them to employ resistive principles, i.e., a layer having low saturated hydraulic conductivity. The most important focus of this study, is the EvapoTranspiration cover (ET) concept, which utilizes one or more vegetated soil layers to retain water until it is either transpired through vegetation, or evaporated from the soil surface. These cover systems rely on the water storage capacity of the soil layer, rather than low hydraulic conductivity materials, to minimize percolation. ET cover designs are based on using the hydrological processes and water balance components at a specific site, which includes the water storage capacity of the soil, precipitation, surface runoff, evapotranspiration and infiltration. The objective of this study is to determine the feasibility of developing and using ET Covers in tropical locations with medium to high precipitation. Puerto Rico can be assimilated as a part and sample of the typical average "Tropical Zones," so the study was concentrated there. The obtained conclusions can be applied later, along with the same principles, to Tropical Zones in general, which will have similar characteristics of rainfall, vegetation, soil texture and classification, and temperature. The study consisted of collecting climate, soil, and vegetation data and characteristics from six regions or "Ecozones" determined on the Island of Puerto Rico, as a representative of the "Tropical Sub-climate." The collected data was then used as input of a software called PR-ET to calculate the PET or ETo of the location and then the basis data of a flow model (HYDRUS 1-D) to simulate infiltration into the waste during peak weather events. PET and ETo are similar terms and are defined as the "Potential Evapotranspiration." Simulations were performed to evaluate the effect of the weather period, the effect of soil thickness, the effect of vegetation, the LAI (Leaf Area Index) and finally to determine what regions in Puerto Rico show potential for implementing ET covers.Results from this study showed some sub-regions (or locations) belonging to the six Ecozones (or regions) of Puerto Rico were able to meet the preliminary requirements for hydrological performance as required by the RCRA. However, field evaluation of these designs should be performed before full implementation of ET covers in these regions. Of the 21 locations studied in the preliminary design, 15 were adequate for study by modeling them to confirm the feasibility of using the Evapotranspiration covers in them. After this modeling or simulation was conducted, the results were as follows: eight locations can effectively use ET covers using as covering vegetation pastures. Five locations can use ET covers, but the vegetation needs to be changed using then shrubs and grass. The other locations are being rejected for this study. The selected locations are supposed to have thickness less than 2.0 m. Show less

ABSTRACT A limited number of studies using various types of cover materials to attenuate H2S emissions have been performed both at the laboratory and field scales. These results have demonstrated that H2S emissions can be effectively reduced using compost, fine concrete, and lime-amended sandy soils as cover materials using several mechanisms (Plaza et al. 2007, Xu, 2005, Sungthong 2010). These mechanisms are: (1) Hydrogen sulfide is consumed by bacteria found in soil that oxidizes hydrogen... Show moreABSTRACT A limited number of studies using various types of cover materials to attenuate H2S emissions have been performed both at the laboratory and field scales. These results have demonstrated that H2S emissions can be effectively reduced using compost, fine concrete, and lime-amended sandy soils as cover materials using several mechanisms (Plaza et al. 2007, Xu, 2005, Sungthong 2010). These mechanisms are: (1) Hydrogen sulfide is consumed by bacteria found in soil that oxidizes hydrogen sulfide to elemental sulfur or sulfate, (2) Clay or organic matter in soils may also sorb hydrogen sulfide (soil microorganisms are not involved in the sorption process), and (3) H2S may be oxidized by reaction with soil minerals, particularly ferric iron. Such mechanisms are well understood from the significant amount of research performed on H2S gas removal using biofiltration. Additionally, under aerobic landfill cover conditions, considerable research has been performed using microbiological methane oxidation to mitigate methane emissions from municipal solid waste. One of the main issues regarding the implementation of approaches for the reduction of H2S emissions from landfills is the lack of a proper technique to assess the level of H2S oxidation and reaction under field conditions. Developing such a technique would allow the determination of H2S oxidation capacity of different cover materials and different cover designs under different climatic conditions. One possible technique that could be employed is the Gas Push Pull Test (GPPT). The general aim of this thesis is to develop the GPPT method for a reactive gas like H2S, which has not been done before. GPPT is a single well gas-tracer test in which inert gases are used as non-reactive tracers for the reactive gas (methane) or in this case, H2S. During the test, a mixture of tracer and reactive gases is injected (pushed) into the soil. During a transition phase, the soil "air" mixes with the injected gases where it is available to microorganisms or minerals. The mixture of soil "air" and injected gas is then extracted (pulled) from the same location. The quantification of oxidation is then based on the analysis of the breakthrough curves (relative concentrations) of the reactive and the tracer gases. It is expected that the tracer concentrations at the injection/extraction points decrease as a result of physical transport processes, whereas the attenuation of the reactive gas is a result of physical transport processes, chemical oxidation, and microbial (and others) activities. A lab study was completed to assess the reactivity of H2S by different soil types typically used in landfill cover construction. The reactivity of H2S was characterized by zeroth-order kinetics as well as correlating the reactivity to water and iron content of the soil materials. The lab study only investigated physical and chemical processes that attenuate H2S. In addition to the laboratory study, a field study was completed to develop proper methods in performing a (GPPT) to measure the capacity of soil materials to oxidize H2S. The objectives were to experimentally compare transport of the reactant gas H2S and tracer gases during GPPTs as a function of varying injection/extraction flow rates in a porous medium and in the absence of microbial activity. Additionally, the relative importance of molecular diffusion, advection, and transfer into the water phase of H2S during GPPTs was also evaluated as well as developing a correction ratio that would allow the use of tracers with dissimilar molecular weights. Show less

Date Issued

2013

Identifier

FSU_migr_etd-7878

Format

Thesis

Title

E.Coli Growth and Transport in the Presence of Nanosilver under Variable Growth Conditions.

Nanosilver has the ability to anchor to the bacterial cell wall and subsequently penetrate it, thereby causing structural changes in the cell membrane and death of the cell. The bacterial responses to the presence of nanosilver usually vary depending on the concentration of nanosilver particles, exposure conditions and the bacterial physiological stage. Since bacterial anabolism dependents upon a stoichiometric ratio of carbon and inorganic nutrients, the carbon to nitrogen ratio (C/N) thus... Show moreNanosilver has the ability to anchor to the bacterial cell wall and subsequently penetrate it, thereby causing structural changes in the cell membrane and death of the cell. The bacterial responses to the presence of nanosilver usually vary depending on the concentration of nanosilver particles, exposure conditions and the bacterial physiological stage. Since bacterial anabolism dependents upon a stoichiometric ratio of carbon and inorganic nutrients, the carbon to nitrogen ratio (C/N) thus plays an important role of bacterial responses to the exposure of nanosilver. This study investigated the responses of Escherichia coli to the exposure of nanosilver under variable growth conditions. It was discovered that E. coli grown under different growth conditions had least resistance to the toxicity of nanosilver when cultured under carbon limited conditions. However, the presence of rhamnolipid, a commonly utilized biosurfactant for soil remediation increased the resistance of E. coli to nanosilver. The transport of E. coli cultured under carbon limited conditions was further studied in silica sand columns. E. coli adsorption in silica sand increased when cultured in the presence of nanosilver. On the contrary, E. coli adsorption in silica sand was significantly reduced when cultured in the presence of rhamnolipid. The results suggest that the resistance of E.coli to nanosilver can be improved by diminishing the carbon limitation in growth condition and the transport impact of nanosilver can be diminished by adding rhamnolipid. Show less

Rhamnolipid biosurfactant is a bacterial biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension, allowing the water to spread out more evenly and better penetrate the hydrophobic soils. Because of its bio-degradability, rhamnolipid biosurfactant applications cause minimal adverse effects to the soil and groundwater as compared with that of chemical wetting agents. Rhamnolipid biosurfactant applications... Show moreRhamnolipid biosurfactant is a bacterial biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension, allowing the water to spread out more evenly and better penetrate the hydrophobic soils. Because of its bio-degradability, rhamnolipid biosurfactant applications cause minimal adverse effects to the soil and groundwater as compared with that of chemical wetting agents. Rhamnolipid biosurfactant applications save water consumption during agricultural irrigation, especially under draught conditions. This research was designed to investigate the effectiveness of rhamnolipid biosurfactant applications in agricultural soils and key functioning properties. Performance of the rhamnolipid biosurfactant was explored in intact soil column experiments using agricultural soil. Investigating the impact of the rhamnolipid biosurfactant wetting agent fate and transport of organic concentration. Concluding rhamnolipid biosurfactants work effectively at low concentrations, from 12 to 6 percent and would be suitable for biosurfactant production and use. Show less

Rhamnolipid biosurfactant is a bacterial biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension, allowing the water to spread out more evenly and better penetrate the hydrophobic soils. Because of its bio-degradability, rhamnolipid biosurfactant applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Rhamnolipid biosurfactant applications... Show moreRhamnolipid biosurfactant is a bacterial biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension, allowing the water to spread out more evenly and better penetrate the hydrophobic soils. Because of its bio-degradability, rhamnolipid biosurfactant applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Rhamnolipid biosurfactant applications save the water consumptions during agricultural irrigation, especially under draught conditions. This research was designed to investigate the applications of rhamnolipid biosurfactant applications in agricultural soils. Performance of rhamnolipid biosurfactant in intact soil columns collected from agricultural soils was explored and related to the soil and wetting agent properties. In addition, the impact of the organic concentration of wetting agent fate and transport was investigated. The results show that Rhamnolipid biosurfactant may lower the water surface tension (relates to Gibbs free energy of the interaction between rhamnolipid biosurfactant molecules), and wet the agricultural soil samples. The critical micelle concentration (CMC) of rhamnolipid biosurfactant, which is defined as the minimum concentration to form the initiate micelle, is about 40 mg/L. Moreover, the adsorption isotherm of rhamnolipid biosurfactant on the soil is inversely proportional to the increase of concentration of surfactant due to the formation of micelle. But this adsorption isotherm is not dependent to the concentration of biochar-amended soils. The column transport of rhamnolipid biosurfactant is also explored. The results show that the thermodynamic properties of rhamnolipid biosurfactant may control its transport. The retention time of rhamnolipid biosurfactant on the soil changes over the time (pore volume) due to its soprtion, but does not relate to the concentration of biochar-amended soil samples. This transport may also be represented by the advection-dispersion equation with a local equilibrium assumption. The results prove that we may apply rhamnolipid biosurfactant and biochar in the agricultural soils in subtropical area. This application will enhance the water containing ability of soil for crop purpose, and improve the properties of soil. Show less

Date Issued

2013

Identifier

FSU_migr_etd-8654

Format

Thesis

Title

The Use of O₃ Advanced Oxidation Processes for Landfill Leachate Pretreatment.

The final discharge point for collected landfill leachates is frequently the local municipal wastewater treatment facility. The salinity, color, and/or nutrient and organics contamination of leachates often necessitate some form of pre-treatment. When advanced oxidation processes (AOPs) are considered for pre-treatment, the unique composition of dissolved organic matter (DOM) and the relatively high concentrations of some inorganic solutes in leachate will inhibit treatment efficiency. The... Show moreThe final discharge point for collected landfill leachates is frequently the local municipal wastewater treatment facility. The salinity, color, and/or nutrient and organics contamination of leachates often necessitate some form of pre-treatment. When advanced oxidation processes (AOPs) are considered for pre-treatment, the unique composition of dissolved organic matter (DOM) and the relatively high concentrations of some inorganic solutes in leachate will inhibit treatment efficiency. The most important benchmark for design of AOPs is the expected steady-state production of free radical (*OH). Without a quantitative assessment of total *OH consumption in high-strength waste water, like a landfill leachate, efficient AOP treatment is uncertain. For this reason, two landfill leachates, distinct in color, DOM, population served by municipal solid waste facility, and age of landfill, were characterized for *OH-scavenging using a well-established competition kinetics method. After stripping the samples of inorganic carbon, the DOM in leachate from mature (stabilized) landfill was found to react with *OH at a rate of 9.76 x 108 M-1s-1. However, DOM in leachate from newer landfill was observed to scavenge available *OH at a faster rate (8.28 x 109 M-1s-1). The combination of fast rate of reaction with *OH and abundance of DOM in the sampled leachate severely limited the contribution of *OH to degradation of an O3- and *OH-labile organic probe compound (bisphenol-a) in the ozonated mature leachate (f*OH= 0.03). Substantial dosing of both O3 and H2O2 (> 70 mg/L and >24 mg/L, respectively) may be required to see at least 1-log-removal (>90%) of an *OH-selective leachate contaminant (parachlorobenzoic acid) in a mature landfill leachate. Show less

Streams of the coastal plain were inventoried and surveyed for large woody material (LWM) in relationship with fluvial geomorphic characteristics. This empirical data was used to identify wood density based on stream channel hydraulic geometry (i.e., width, depth, and cross sectional area) and the relationship to bankfull discharge and watershed area. Drainage area and stream bankfull width were determined to be correlated with total volume and number of pieces of LWM, providing predictive... Show moreStreams of the coastal plain were inventoried and surveyed for large woody material (LWM) in relationship with fluvial geomorphic characteristics. This empirical data was used to identify wood density based on stream channel hydraulic geometry (i.e., width, depth, and cross sectional area) and the relationship to bankfull discharge and watershed area. Drainage area and stream bankfull width were determined to be correlated with total volume and number of pieces of LWM, providing predictive capability for the natural abundance of LWM in streams of the coastal plain. Following its restoration, Anderson Branch was inventoried for in-stream LWM and monitored for stability. Minimal variability observed in the dimension, pattern, and profile of the stream channel was attributed to the proper placement and density of LWM. Streams of the coastal plain were also surveyed for the contribution of sandbed formations and woody material to channel roughness. The protrusion height of sandbed formations and woody material were determined to be a better estimate of Manning's n than bed material size, providing improved guidance in restoration practices as well as a more accurate method of predicting bankfull discharge in the event a gage/and or regional curve is unavailable. Show less

Florida provides some of the most diverse and beautiful environments in the United States, with northwest Florida being a nearly undisturbed bounty of lush lands, springs, and other geological and ecological features. Increases in population have recently started to jeopardize some of Florida's prized areas, including the Ochlocknee-St Marks Basins. Development and agriculture has started to affect watersheds and waterbodies. This study has evaluated the water quality of coastal marshes at... Show moreFlorida provides some of the most diverse and beautiful environments in the United States, with northwest Florida being a nearly undisturbed bounty of lush lands, springs, and other geological and ecological features. Increases in population have recently started to jeopardize some of Florida's prized areas, including the Ochlocknee-St Marks Basins. Development and agriculture has started to affect watersheds and waterbodies. This study has evaluated the water quality of coastal marshes at the St. Marks national Wildlife Refuge in terms of coliform and chlorophyll a. With these constituents, dissolved oxygen (DO), temperature, pH, conductivity, and total suspended solids were evaluated. The study took place with data from January 2009 to June 2009. The study site of this research, St. Marks National Wildlife Refuge, is located 25 miles south of Tallahassee along the Gulf Coast of Florida. To analyze for coliform, 100ml samples were filtered on cellulose nitrate membranes and subsequently incubated. After 24hrs the fecal coli forms were counted and recorded. Measuring the chlorophyll a was done taking a volume of water from a particular depth and filtering it through a fine glass fiber filter to collect all of the particulate material great than 1 micron. To extract the chlorophyll, acetone/alcohol was used as a solvent and then measured using an optical kit and Luminometer utilizing a chlorophyll a standard. Effective diffusion was then measured in the lab using a diffusion coefficient in distilled water. This process was also observed using a Hamamatsu high sensitivity monochrome digital camera in a dark room, with the sample being placed in a petri dish with native soil. Chlorophyll a adsorption was measured by introducing the sample to a column filled with goethite-coated silica sand. Transport parameters were obtained by fitting the experimentally obtained Chlorophyll a breakthrough data using an implicit, finite-difference scheme. All the parameters were optimized by minimizing the sum of squared differences between observed and fitted concentrations using the nonlinear least-square method. Some key observations over the sample period include the dropping of DO as the summer months began indicating increased microbial activity with temperature. TKN and Chlorophyll were observed to increase as temperature increased. When observing Chlorophyll as a function of TKN, the Pearson Correlation and the plot indicate that with increased TKN more microbiological activity occurs - such as with plants, algae, etc. Interestingly when Chlorophyll was plotted as a function of DO, the low DO encourages microbial growth, however only to an extent. The point can be made that less polluted water has less microbial activity. The correlation between coliform and turbidity showed an increase of coliform with NTU. Chlorophyll as a function of turbidity showed no correlation. However as a first order function, d[Chlorophyll a]/d[Turbidity] displayed a linear relationship with turbidity, indicating the correlation of chlorophyll a variation with respect to turbidity. When conductivity was plotted against pH, the variability of conductivity and pH was not significantly different. Chlorophyll a also had a correlation with pH. With the increase of pH, chlorophyll a exponentially decreased. This research shows the increased ability to forecast and assess risk presented by development and agriculture of coastal environment based on physical and chemical variations in coastal wetland ecosystems. Show less

National Water-Quality Assessment Program (NAWQA) was designed just after the U.S. Geological was established. The primary objective of the NAWQA was to understand the key processes controlling contaminant fate and transport into the Nation's water resources. In particular, wide use of pesticides and fertilizers in agricultural field can impact on the quality of surface and ground waters. Contaminants can be carried to the water bodies by several ways. In colloid-facilitated transport process... Show moreNational Water-Quality Assessment Program (NAWQA) was designed just after the U.S. Geological was established. The primary objective of the NAWQA was to understand the key processes controlling contaminant fate and transport into the Nation's water resources. In particular, wide use of pesticides and fertilizers in agricultural field can impact on the quality of surface and ground waters. Contaminants can be carried to the water bodies by several ways. In colloid-facilitated transport process colloidal particles serves as a transport media for the contaminants. Colloid release from the agricultural soil under unsaturated conditions is controlled by the hydrodynamic force, capillary force and electrostatic force that is determined by the solution chemistry in terms of solution ionic strength and pH. In this research, colloid release from the agricultural soil was investigated using an intact soil column collected from an agricultural site in Gadsden County of Florida. Colloid release was monitored and the colloid release curve was simulated using an implicit, finite-difference scheme to obtain the colloid release coefficient. It was found that the hydrodynamic force and electrostatic force overcame the capillary force under the experimental conditions of this research and consequently, colloids were released. For the colloid release, solution chemistry played a key role by controlling the colloid repulsive electrostatic force within the pore system. Colloid release exponentially decreased with the increase of solution ionic strength and increased with the increase of solution pH. Colloid release was finally found to be correlated to the colloid repulsive electrostatic force within the pore system, i.e., the greater the repulsive electrostatic force, more colloids were released. In situ colloid mobilization and transport has been studied under both saturated and unsaturated conditions. In saturated conditions, the controlling parameters are solution ionic strength and pH. Colloid mobilization and transport have been modeled by the advection-dispersion equation with a first-order colloid release. The inverse version of these models can provide a platform to estimate transport parameters based on transport observations. In this research, we taken the advantages of existing contaminants transport models by fully utilizing them to investigate colloid interactions with the surrounding environment and provide parameter constraints for colloid transport modeling applications under saturated conditions. In natural systems, colloids present a potential health risk due to their propensity to associate with contaminants or in the case of certain biological colloids, inherent pathogenic nature. Although colloidal interactions have been studied for many years and much has been learned about the physical and chemical processes that control colloid retention, there still remains significant uncertainty about the processes that govern colloid release. The aim of this study was to investigate the release of in situ colloids as a function of soil depth. Colloid release from intact agricultural soil columns with variable length was investigated. Colloid release curves were simulated using an implicit, finite-difference scheme and colloid release rate coefficient was found to be an exponential function of the soil depth. The simulated results demonstrated that transport parameters were not consistent along the depth of the soil profile. Wetting agents wet hydrophobic soil by lowering the cohesive and/or adhesive surface tension, which allows the water to spread out more evenly and allows for better penetration into the hydrophobic soils. While enhancing water penetration, wetting agent applications may bring adverse impact on the soil and groundwater at the same time. The residual organic phase in the soil pores poses a long-term source of groundwater contamination. After use, residual wetting agents and their degradation products are discharged to groundwater or directly to surface waters, then dispersed into different environmental compartments. In order to assess their environmental risks, we need to understand the distribution, behavior, fate and biological effects of these surfactants in the environment. This research was designed to investigate the application of nonionic wetting agents in agricultural soils. Performance of nonionic surfactants in intact soil columns collected from agricultural soils was explored and related to the soil and wetting agent properties. In addition, the impact of the organic concentration of wetting agent fate and transport was investigated. The transport of wetting agents in the agricultural soil columns was simulated using the proposed transport models and subsequently, the effect of organic compounds on wetting agent transport was quantified. Show less